The invention relates generally to the field of detecting segment boundaries in digitized video and, more particularly, to detecting such segment boundaries in digitized video originating from camcorders having a mosaic fade feature.
A variety of camcorders are currently available for personal and professional videotaping. These camcorders are capable of recording and storing hours of video from which the user may desire to extract the salient content and/or perform automatic summarization. There are currently a variety of prior art methods available for detecting segment boundaries to assist in this extraction and summarization.
A segment is usually defined as a temporally ordered sequence of frames captured by one camera in a single operation. The simplest type of segment boundary to detect is a cut, typified by an abrupt change in the content of the image frame. This occurs when one continuous operation of a camera has ceased, and another has begun. These segment boundaries can be detected through a variety of currently available means including color histogram differences and pixel differences between adjacent frames.
However, special effects added during capture or editing introduce other types of segments whose boundaries that can be very difficult to detect because of their nuances. These special effect transitional segments include fades, dissolves, and wipes.
Many camcorders and video editing suites currently have a fade feature in which, for a fade out, a normal image is gradually darkened until the image is completely black, or for a fade in, a completely black image is gradually lightened until the image is normal. The boundaries of these transitional segments can be detected through a variety of currently available means including tracking the changes in image illumination.
A similar type of transitional segment currently available in many camcorders and video editing suites is a mosaic (or tiled) fade. A mosaic fade is similar to a traditional fade in that one end of the fade displays a normal image while the other end displays an image with little or no meaningful content. A typical traditional fade out begins with a normal image, and as the sequence progresses, each consecutive frame is darker than the preceding one until the frame contains nothing but black. In a mosaic fade out, the apparent resolution of the image is decreased until the image appears to break up into an array of uniformly colored tiles that grow in size until the frame contains only a few large tiles.
It is noted that some camcorders embed time and date information into the data stream. While many currently popular consumer video formats support time and date data embedding, the cost of implementation has relegated this feature to only a few high-end analog camcorders; this time and date information is typically available in most digital camcorders. If available, the time and date information simplifies the task of cut detection and aids in the detection and identification of special effect transitions.
Time and date information aids in the detection of special effect transitions by identifying temporal discontinuities that occur at one end of the transitional segment. Even with this information, the frames leading to and from the segment boundary must be examined to determine the presence and character of special effect transition(s). However, if this information is unavailable, the detection of these special effect transitions and their attendant boundaries by prior art methods is more difficult, if detectable at all.
Consequently, a need exists for detecting mosaic fades and identifying their boundaries in digitized video containing them.
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention, the invention resides in a method for automatically detecting a segment where a mosaic fade, formed by a plurality of tiles, occurs in a digital video, the method comprising the steps of: locating the segment of the digital video containing the plurality of tiles in each frame; detecting whether the tiles, within the located segment, have a predetermined increase or decrease in size from one frame to a next frame; identifying a boundary of the mosaic fade based on step (b).
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
The present invention has the advantage of detecting mosaic fades in digitized video.